Project Summary In the project, "Recovering Individual Memory Problems Histories from Own and Proxy Retrospective Reports: A Feasibility Study," we will adapt and extend the well-known Langa- Weir method to estimate the prevalence of Alzheimer’s Disease and Related Dementias (ADRD) over the life-course of individuals. Our aims are explore whether and under what conditions one can use that method to identify incipient ADRD in earlier life stages and how well the method works. We focus specifically on ADRD not only because it is a critical issue faced by most of the world’s populations but also because it is part of a class of diseases that share two important features. First, in early stages of ADRD, patients present symptoms that are difficult to interpret and that might be caused by multiple and very different diseases. Second, after a person clearly has ADRD, that person increasingly finds it more and more difficult to remember and report whether and when their symptoms began. The first characteristic implies that, compared to contemporaneously collected data, retrospectively reported data might better measure prevalence in populations at the early stages of ADRD. The second characteristic implies that self-reported retrospective data will likely be less accurate than retrospective reports of proxy respondents (who know the respondent’s history). Our project leverages, complements, and benefits from the approach, data, and structure in our recently funded R21 project titled, “Constructing, Validating, and Testing the Predictive Power of Life-Course Health Histories.” In particular we will use the life course histories of other diseases as covariates in our model to predict incipient ADRD. This supplemental project will dive more deeply into the specific issues associated with ADRD. As in the parent project, our overall aims are to conduct a “proof-of- concept” exercise to explore whether and for what conditions one can use retrospective questions to generate life health histories and to provide a guide for researchers to use. Our work products will expand the set of questions researchers can address with retrospective health data already collected on existing surveys. The supplemental project will yield insights on the specific issues associated with ADRD.

Project Narrative "Recovering Individual Memory Problems Histories from Own and Proxy Retrospective Reports: A Feasibility Study," will adapt and extend the well-known Langa-Weir method to estimate the prevalence of Alzheimer’s Disease and Related Dementias (ADRD) over the life-course of individuals. This proof-of-concept project focuses on specific issues and challenges of using retrospectively reported data on memory problems to identify people likely to develop ADRD in later life. The supplement and parent projects leverage enormous investments the scientific community has made to measure population and individual health on cross-sectional and longitudinal surveys.